双层涡旋气流等离子弧切割工艺及机理研究

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1、摘要摘要等离子弧切割具有适用范围广、切割速度快、精度高、成本低等优点，广泛应用于船舶、桥梁、机械等重型装备及钢结构制造。本文研究了切割工艺参数对双层涡旋气流等离子弧切口质量的影响，从而为正确制定相关切割工艺，以提高切割质量和效率提供指导。试验结果表明：随着切割速度的增大及切割电流的减小，切口上下宽度减小、斜角增大；切割速度及电流增大，切口面挂渣程度减小。同时，低速侧切口面斜角小、挂渣多，适当切割速度下可以获得接近垂直的切口。此外，双层氧气等离子弧切割，切口面光洁、挂渣少，但上下口宽度大，且在低速切割时切口容易出现锯齿波状和负倾角；双层空气等离子弧切割时，得到单侧垂直切口的切割速度范围

2、最宽。另外，本文通过合理假设，建立了等离子切割电弧的数学模型，并利用ANSYS软件对电弧的温度场和流场进行了数值计算与分析，为后续对双层涡旋气流等离子切割电弧的数值计算打下基础。计算结果表明：电弧温度和内部粒子流速，分别随着沿轴线距离的增大，总体呈现先增大后减小的趋势；与等离子焊接电弧相比，等离子切割电弧温度分布显得更为集中。此外，随着切割电流的增大和喷嘴孔径的减小，电弧平均温度上升，且电弧内部粒子流速增大。计算结果与理论及有关文献基本符合。关键词：双层涡旋气流，等离子弧切割，切口质量，有限元法，ANSYSIAbstractAbstractPlasmaarccuttinghasthe

3、advantagessuchasawideapplication,fastcuttingspeed,hightoleranceandlowcost,andhasbeenwidelyappliedindockyards,bridges,aswellasmachineriesofotherheavyequipmentindustriesandconstructionsofsteelstructure.Thispaperdiscussestheeffectsofparametersonthekerfqualityofplasmaarccuttingtocorrectlyadjustthep

4、arametersofdualswirlingplasmaarccutting,toprovidetheoreticalbasisforimprovingthekerfqualityandcuttingefficiency.Theexperimentalresultsshowthatwiththecuttingspeedincreasesandthecurrentdecreases,thewidthofkerfdecreasesandthebevelangleincreases.Thedrossattachedlevelobviouslydecreaseswiththecutting

5、speedandcurrentincreases.Atthesametime,thebevelangleoflowspeedsideobviouslybellowsthatofhighspeedside,however,thedrossattachedisopposite.Wecanobtainaverticalkerfononesidewhenthecuttingspeedisappropriate.Inaddition,whenweusedualOxygen,thekerfhasasmoothcutsurfaceandlessdrossattached.However,thewi

6、dthofkerfincreasesandthekerfgetsashapelikesawtoothandanegativebevelangleeasilyunderthelowcuttingspeed.Therangeofcuttingspeedtogetaverticalkerfononesideismostlywideunderthedualaircondition.Inaddition,thispaperestablishesanumericalmodelofthearcinplasmaarccuttingaccordingtoreasonableassumptionsand

7、simulatesthetemperatureandvelocityfieldofthearcusingANSYSinordertogiveabasistosimulatethearcindualswirlingplasmaarccutting.Thecalculationresultsshowthetemperatureofarcandvelocityofparticlesgenerallyfirstincreasesthendecreaseswitht